1. Field of the Invention
This invention relates generally to medical devices for accessing a patient's circulatory system. More particularly, this invention relates to improved-safety assemblies used for withdrawing blood from and administering therapeutic fluids to a patient connected to intravenous or intraarterial lines.
2. Description of Related Art
It is common practice in hospitals to administer therapeutic fluids through or draw blood for laboratory studies from intravenous or intraarterial ("IV") lines connected to patients. This practice avoids the discomfort and risk a patient would experience from additional needle sticks required to directly access the patient's circulatory system.
Generally, IV lines are equipped with a multi-port stopcock. In typical practice, a blood sample is obtained by disrupting the flow of IV fluid to the patient through one port with a turn of the stopcock, attaching a syringe to a second port of the stopcock, withdrawing blood contaminated with IV fluid from the line, attaching a new syringe to the second port of the stopcock and, finally, drawing a sample. The initially drawn sample of blood contaminated with IV fluid may be reinjected or discarded. In any case, the first port of the stopcock is opened to the IV fluid supply and the IV line is then flushed with fluids.
A blood sample to be used for laboratory studies is typically transferred to an evacuated container by placing a hypodermic needle on the syringe and pushing the needle cannula through the rubber stopper of the evacuated container so that the blood is drawn into the container by the vacuum until the container is filled or the syringe is empty.
Unfortunately, this technique for drawing laboratory samples has several serious shortcomings. First, stopcocks are a common source of nosocomial infections since they become contaminated with blood and IV fluids during the withdrawal and reinfusion steps. Second, this method of transferring blood is costly since the equipment is relatively expensive and the intravenous tubing with stopcocks must be replaced frequently to minimize the occurrence of nosocomial infections. Third, and most important, this method of blood transfer requires extreme skill and care to avoid injury to hospital personnel. Specifically, needle stick injuries are likely to occur since the syringe must be equipped with a hypodermic needle and the hypodermic needle must then be guided toward an evacuated container held in the hand of hospital personnel. Needle sticks may also occur during recapping of the needles or later, during clean-up procedures.
Accidental needle sticks with blood contaminated needles represent a major health problem to hospitals, other medical facilities, and their personnel. It is estimated that there are 800,000 needle sticks per year in the United States resulting in a cost for testing and care of approximately $500,000,000. While needle sticks have been a problem since the invention of hypodermic needles, the recognition of the transfer of the AIDS virus by needle sticks has amplified concern over this problem. A number of other viral and bacterial infections (e.g., Hepatitis B, tuberculosis, and malaria) can also be transmitted by accidental needle stick injuries.
The same problems may occur when therapeutic fluids (for example, antibiotics, chemotherapeutics, and nutrients) are administered through IV lines. Therapeutic fluids may be administered to a patient connected to IV lines by equipping a syringe with a hypodermic needle, inserting the needle cannula into a container filled with the therapeutic fluid and drawing a desired amount, and then inserting the needle directly into the IV fluid container, or a piggyback container if present, through an injection port generally provided on these containers. Alternatively, the needle may be removed from the fluid containing syringe, the syringe attached to the stopcock and therapeutic fluid administered through it. Again, if extreme care is not taken with either method, needle stick injuries may occur during attachment of the hypodermic needle to the syringe, during the handling of the syringe equipped with the hypodermic needle, during removal of the needle from the syringe, during recapping of the needle, or during clean-up procedures.
Most research on the prevention of needle stick injuries has been directed towards developing safer needle caps. However, to date no solutions to the above-referenced multiple problems associated with blood and other fluid transfer have been disclosed.